This section provides background information related to the present disclosure, which is not necessarily prior art. During cold engine starts, it is desirable to warm the engine as quickly as possible, such as by warming engine coolant, to optimize engine performance and efficiency. While systems for warming engine coolant are suitable for their intended use, they are subject to improvement. The present teachings advantageously include improved systems for warming engine coolant, particularly during a cold engine start. The systems according to the present teachings advantageously reduce engine warm-up time, which reduces vehicle emissions, improves fuel economy, and reduces cabin warm-up time, for example. The present teachings provide for numerous additional advantages and unexpected results, as described herein and as one skilled in the art will appreciate.